AbstractNiFe2O4/polythiophene nanocomposite was synthesized by in situ chemical oxidative polymerization of thiophene in NiFe2O4 nanoparticles presence, whereas NiFe2O4 nanoparticles were prepared via coprecipitation method. Fourier transform infrared (FTIR), X‐ray diffraction (XRD), UV–Visible, and SEM, EDX techniques were used for characterization of the nanocomposite. The effect of various parameters such as adsorbent dose, contact time, initial dye concentration, and initial pH of solution on the adsorption of Janus green B (JG) and Fuchsin basic (FB) onto the nanocomposite was optimized by batch studies. The equilibrium uptake data ascribed well to the Langmuir model with maximum adsorption capacity of 143 and 498 mg/g at 303 K for JG and FB, respectively. The exceptional high adsorption capacity of NiFe2O4/polythiophene nanocomposite for JG and FB was ascribed to π‐π and electrostatic interactions. Kinetics studies pointed out that JG and FB removal followed pseudo‐second order model. The negative values of ΔH° (JG: –47.28; FB: −38.00 kJ/mol) and ΔG° (JG: −9.347 to −6.442; FB: −14.16 to – 12.85 kJ/mol) pointed out the feasibility, spontaneity, and exothermic nature of removal process. Negative value of ΔS° (JG: –0.125; FB: –0.078 kJ/mol) suggested decrease in randomness at the solid/liquid interface. The results showed that NiFe2O4/polythiophene is an appealing adsorbent for the uptake of JG and FB dyes from aquatic environment.